Tue·Jul 21, 2015Tuesday·July 21, 2015

1. 01*

   Centrality and transverse momentum dependence of elliptic flow of multi-strange hadrons and $\varphi$ meson in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV

   STAR Collaboration: L. Adamczyk · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · I. Alekseev · A. Aparin · D. Arkhipkin · E. C. Aschenauer · G. S. Averichev · X. Bai · V. Bairathi and 323 other authors

   We present high precision measurements of elliptic flow near midrapidity ($|y|<1.0$) for multi-strange hadrons and $\varphi$ meson as a function of centrality and transverse momentum in Au+Au collisions at center of mass energy $\sqrt{s_{NN}}=$ 200 GeV. We observe that the transverse momentum dependence of $\varphi$ and $\Omega$ $v_2$ is similar to that of $\pi$ and $p$, respectively, which may indicate that the heavier strange quark flows as strongly as the lighter up and down quarks. This observation constitutes a clear piece of evidence for the development of partonic collectivity in heavy-ion collisions at the top RHIC energy. Number of constituent quark scaling is found to hold within statistical uncertainty for both 0-30$\%$ and 30-80$\%$ collision centrality. There is an indication of the breakdown of previously observed mass ordering between $\varphi$ and proton $v_2$ at low transverse momentum in the 0-30$\%$ centrality range, possibly indicating late hadronic interactions affecting the proton $v_2$.

   nucl-exhep-exhep-phnucl-thPRL(2016)·120 citations
2. 02*

   Gamma Rossi-alpha, Feynman-alpha and Gamma Differential Die-Away concepts as a potential alternative/complement to the traditional thermal neutron based analysis in Safeguards

   Dina Chernikova · Syed F. Naeem · Nermin Trnjanin · Kåre Axell · Anders Nordlund

   A new concept for thermal neutron based correlation and multiplicity measurements is proposed in this paper. The main idea of the concept consists of using 2.223 MeV gammas (or 1.201 MeV, DE) originating in the 1H(n,gamma)2D-reaction instead of using traditional thermal neutron counting. Results of investigations presented in this paper indicate that gammas from thermal neutron capture reaction preserve the information about the correlation characteristics of thermal (fast) neutrons in the same time scale. Therefore, instead of thermal neutron detectors (or as a complement) one may use traditional and inexpensive gamma detectors, such NaI, BGO, CdZnTe or any other gamma detectors. In this work we used D8x8 cm2 NaI scintillator to test the concept. Thus, the new approach helps to address the problem of replacement of 3He-counters and problems related to the specific measurements of spent nuclear fuel directly in the spent fuel pool. It has a particular importance for nuclear safeguards and security. Overall, this work represents the proof of concept study and reports on the experimental and numerical evidence that thermal neutron capture gammas may be used in the context of correlation and multiplicity measurements. Investigations were performed for a 252Cf-correlated neutron source and an 241Am-Be-random neutron source. The related idea of Gamma Differential Die-Away approach is investigated numerically in this paper as well, and will be tested experimentally in a future work.

   nucl-exphysics.ins-detNucl.Instrum.Meth.A(2016)·0 citations
3. 03*

   The study of the thermal neutron flux in the deep underground laboratory DULB-4900

   V. V. Alekseenko · Yu. M. Gavrilyuk · A. M. Gangapshev · A. M. Gezhaev · D. D. Dzhappuev · V. V. Kazalov · A. U. Kudzhaev · V. V. Kuzminov · S. I. Panasenko · S. S. Ratkevich · D. A. Tekueva · S. P. Yakimenko · Yu. V. Sten'kin

   We report on the study of thermal neutron flux using monitors based on mixture of ZnS(Ag) and LiF enriched with a lithium-6 isotope at the deep underground laboratory DULB-4900 at the Baksan Neutrino Observatory. An annual modulation of thermal neutron flux in DULB-4900 is observed. Experimental evidences were obtained of correlation between the long-term thermal neutron flux variations and the absolute humidity of the air in laboratory. The amplitude of the modulation exceed 5\% of total neutron flux.

   nucl-exphysics.ins-detPhys.Part.Nucl.(2017)·4 citations
4. 04*

   $\bar{D}{\Sigma }_c^{\ast }$ and ${\bar{D}}^{\ast }{\Sigma }_c$ interactions and the LHCb hidden-charmed pentaquarks

   Jun He🇨🇳

   Very recently, two hidden-charmed resonances $P_c(4380)$ and $P_c(4450)$ consistent with pentaquark states were observed at the LHCb detector. The two $P_c$ states locate just below the $\bar{D}{\Sigma }_c^{\ast }$ and ${\bar{D}}^{\ast }{\Sigma }_c$ thresholds with mass of gaps about 5 and 15 MeV, respectively. Inspired by this fact we perform a dynamical investigation about the $\bar{D}{\Sigma }_c^{\ast }(2520)$ and ${\bar{D}}^{\ast }{\Sigma }_c(2455)$ interactions which are described by the meson exchanges. A bound state which carries spin-parity $J^P=3/2^{-}$ is produced from the $\bar{D}{\Sigma }_c^{\ast }(2520)$ interaction, which is consistent with the $P_c(4380)$ observed at the LHCb detector. From the $D^{\ast }{\Sigma }_c(2455)$ interaction, a bound state with $5/2^{+}$ is produced, which can be related to the $P_c(4450)$. The results suggest that the $P_c(4380)$ and $P_c(4450)$ are good candidates of $\bar{D}{\Sigma }_c^{\ast }(2520)$ and ${\bar{D}}^{\ast }{\Sigma }_c(2455)$ molecular states, respectively.

   ↳ hep-phhep-exhep-latnucl-ex+1PLB(2016)·256 citations
5. 05*

   Understanding the newly observed heavy pentaquark candidates

   Xiao-Hai Liu🇯🇵 · Qian Wang🇩🇪 · Qiang Zhao🇨🇳

   We find that several thresholds can contribute to the enhancements of the newly observed heavy pentaquark candidates $P_c^{+}(4380)$ and $P_c^{+}(4450)$ via the anomalous triangle singularity (ATS) transitions in the specific kinematics of ${\Lambda }_b\to J/\psi K^{-}p$. Apart from the observed two peaks we find that another peaks around 4.5 GeV can also be produced by the ATS. We also show that the ${\Sigma }_c^{(\ast )}$ can be produced at leading order in ${\Lambda }_b$ decay. This process is different from the triangle diagram and its threshold enhancement only appears as CUSP effects if there is no pole structure or the ATS involved. The threshold interaction associated with the presence of the ATS turns out to be a general phenomenon and plays a crucial role in the understanding of candidates for exotic states.

   ↳ hep-phhep-exnucl-exnucl-thPLB(2016)·288 citations
6. 06*

   Thermodynamics of the low density excluded volume hadron gas

   Krzysztof Redlich🇵🇱 · Kacper Zalewski🇵🇱

   We consider thermodynamics of the excluded volume particles at finite temperature and chemical potential, in the low density approximation. We assume Boltzmann statistics and study the influence of the excluded volume on an ideal gas thermodynamics at the same temperature, pressure and numbers of particles. We show, that considering the change of the free enthalpy due to the excluded volume, and using the Maxwell identities, one can derive relevant thermodynamic functions and parameters of multi-component gases. The derivation is quite general as particles may have different sizes and shapes which can also depend on their momenta. Besides it's simplicity and generality, our approach has the advantage of eliminating the transcendental equations occurring in earlier studies. A representative example of the excluded volume thermodynamics is the single-component gas of hard spheres. For this case, using the viral expansion, the validity limits of the low-density approximation are also discussed.

   ↳ hep-phnucl-exPRC(2016)·16 citations
7. 07*

   JUNO and Neutrinoless Double Beta Decay

   Shao-Feng Ge🇩🇪 · Werner Rodejohann🇩🇪

   We study the impact of the precision determination of oscillation parameters in the JUNO experiment on half-life predictions for neutrinoless double beta decay. We show that the solar neutrino mixing angle can be measured by JUNO with below 1% uncertainty. This implies in particular that the minimal value of the effective mass in the inverted mass ordering will be known essentially without uncertainty. We demonstrate that this reduces the range of half-life predictions in order to test this value by a factor of two. The remaining uncertainty is caused by nuclear matrix elements. This has important consequences for future double beta decay experiments that aim at ruling out the inverted mass ordering or the Majorana nature of neutrinos.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2015)·26 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.